1. Field of the Invention
The present invention relates to a method of making, in near-real-time, a projectile in a trajectory act at a point, known in distance and height, by means of calculated angle of elevation and time of flight. The method can be used either as a pc-based support or as a component in an integrated system for delivering projectiles.
2. Description of Related Art
The lateral alignment (azimuth) will not be discussed here, but is assumed to take place in some prior-art manner, for instance by direct measurement of the direction to a target.
3. Summary of the Invention
The optimising method consists essentially of two parts, a calculation part which discretely timed calculates positions and associated points of time along a trajectory, and a logic part which sets a first direction of elevation, monitors the calculation in the calculation part and interrupts the same when a calculated position lies outside predetermined limit values and, after that, sets a second direction of elevation etc. The logic part determines and establishes two solutions in the form of direction of elevation and time of flight.
The optimising method is intended for trajectory systems that have been subjected to launch trial to such an extent that specific properties of the air drag parameters of the grenade/projectile could be identified. The method can also be used for the actual identification of the air drag parameters. For projectiles with a higher initial velocity, it is possible, by launch trial, to carry out identification of the possible dependence of the air drag on temperature, atmospheric pressure and air humidity. Based on an established relationship of this kind, the thus variable air drag can be used in the calculations in a variant of the invention, which will be possible since the current height in each time step is available.
Based on the measured position of a target, the method can be used to obtain, quickly and with the selected accuracy, a response to how the launching device is to be elevated in order to reach the target. The method also supplies output data for the required time of flight that will be needed in the trajectory from firing until the grenade/projectile reaches the target.
When you want to lead away enemy missiles using countermeasure ammunition, you have a tactical idea that causes a desired specific trajectory pattern. To be able to achieve this pattern, you must know how the launching device is to be elevated and also the time until the effect of the intended countermeasure. It is easy to describe target positions in distance, height and azimuth based on the tactical idea, but it is not easy to reach them using previously known methods. In such countermeasure systems, the time from the discovery of a threat until the time when the effect at predetermined target positions round one's own position, a ship etc, is desired, is short-in many cases very short. This requires extreme rapidity of a system for calculating the alignment of launching device and for fuse time setting of grenades. It is such a system that has been the incentive in the conception of the invention. However, the invention can also be used in other systems which give trajectories, such as in grenade launchers and howitzers, and in support for prediction algorithms for fighting against moving targets using automatic guns and the like. Applicant has the pronounced opinion that the invention should relate to all applications of the inventive method.
The present invention means concretely that the distance and height can be replaced by angle of elevation which directly can control a launcher. Using grenades with variable fuse time setting, it will then be possible to reach the correct position at the desired point of time. In the example involving naval launchers, chaff can be made to blossom out or a pyrotechnic charge can be initiated.
The invention replaces the use of unreliable firing diagrams which often are most inaccurate and solves the problem of making, in near-real-time, a projectile in a trajectory act at a point, known in distance and height, at a desired point of time. This occurs by the invention being designed as will be evident from the independent claim. Suitable embodiments of the invention will appear from the remaining claims.
4. Brief Description of The Drawings